This paper investigates residual stresses in selective laser sintering (SLS) and selective laser melting (SLM) processes. The study aims to understand the phenomenon of residual stresses and their impact on the mechanical properties of the produced parts. A theoretical model is developed to predict residual stress distributions, and experimental methods are used to measure residual stress profiles in test samples produced with different process parameters. Residual stresses are found to be very large in SLM parts. The residual stress profile typically consists of two zones of large tensile stresses at the top and bottom of the part, and a large zone of intermediate compressive stress in between. The magnitude and shape of the residual stress profiles are influenced by material properties, sample and substrate height, laser scanning strategy, and heating conditions. The origin of residual stresses is discussed, with two main mechanisms identified: the temperature gradient mechanism (TGM) and the cool-down phase of the molten top layers. The TGM mechanism results from large thermal gradients around the laser spot, leading to compressive strains in the heated top layer and tensile stress in the lower part. The cool-down phase of the molten top layers leads to tensile stress in the added top layer and compressive stress below. A simplified theoretical model is developed to predict the residual stress profiles. The model considers the base plate and the part being built, and calculates the stress distribution based on the material properties, layer thickness, and other parameters. The model is validated with experimental results, showing that the stress at the last added layer equals the yield stress of the material. The influence of the number of layers, base plate geometry, and material properties on the residual stress profiles is analyzed. The results show that the number of layers, base plate height, and material yield strength significantly affect the residual stress levels. The stress profiles are found to be more uniform with a thicker base plate and higher yield strength. The paper also presents an experimental method called the Crack Compliance Method (CCM) to measure residual stresses. The method involves measuring the deformation of the part when the stresses are relieved. The results show that the CCM method can accurately measure residual stresses, although there are some limitations in measuring the stress at the part surface. The study concludes that residual stresses in SLS and SLM parts are significant and can affect the mechanical properties of the parts. The residual stress profiles are influenced by various factors, including the number of layers, base plate geometry, and material properties. The results suggest that the stress levels can be reduced by optimizing the process parameters and applying heat treatment. The study also highlights the importance of understanding and controlling residual stresses in additive manufacturing processes.This paper investigates residual stresses in selective laser sintering (SLS) and selective laser melting (SLM) processes. The study aims to understand the phenomenon of residual stresses and their impact on the mechanical properties of the produced parts. A theoretical model is developed to predict residual stress distributions, and experimental methods are used to measure residual stress profiles in test samples produced with different process parameters. Residual stresses are found to be very large in SLM parts. The residual stress profile typically consists of two zones of large tensile stresses at the top and bottom of the part, and a large zone of intermediate compressive stress in between. The magnitude and shape of the residual stress profiles are influenced by material properties, sample and substrate height, laser scanning strategy, and heating conditions. The origin of residual stresses is discussed, with two main mechanisms identified: the temperature gradient mechanism (TGM) and the cool-down phase of the molten top layers. The TGM mechanism results from large thermal gradients around the laser spot, leading to compressive strains in the heated top layer and tensile stress in the lower part. The cool-down phase of the molten top layers leads to tensile stress in the added top layer and compressive stress below. A simplified theoretical model is developed to predict the residual stress profiles. The model considers the base plate and the part being built, and calculates the stress distribution based on the material properties, layer thickness, and other parameters. The model is validated with experimental results, showing that the stress at the last added layer equals the yield stress of the material. The influence of the number of layers, base plate geometry, and material properties on the residual stress profiles is analyzed. The results show that the number of layers, base plate height, and material yield strength significantly affect the residual stress levels. The stress profiles are found to be more uniform with a thicker base plate and higher yield strength. The paper also presents an experimental method called the Crack Compliance Method (CCM) to measure residual stresses. The method involves measuring the deformation of the part when the stresses are relieved. The results show that the CCM method can accurately measure residual stresses, although there are some limitations in measuring the stress at the part surface. The study concludes that residual stresses in SLS and SLM parts are significant and can affect the mechanical properties of the parts. The residual stress profiles are influenced by various factors, including the number of layers, base plate geometry, and material properties. The results suggest that the stress levels can be reduced by optimizing the process parameters and applying heat treatment. The study also highlights the importance of understanding and controlling residual stresses in additive manufacturing processes.